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POCursor in Linked List changing value for no apparent reason
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copied!<p><em><strong>Edit</em></strong></p> <p><em><strong>For simplicity:</em></strong> I just want to make the most basic possible cursor that simply goes trough my list without changing in any way / shape or form my "begin". I still want begin to be changed when I return something though, just not before. So is it possible to make a pointer to begin, go trough the list without changing anything except at the very end when I want to add a new node ?</p> <p><em><strong>Also</em></strong> Can I just go trough the list with a simple pointer that is not a "Node" ?</p> <p><em><strong>/Edit</em></strong></p> <p>I have a simple (singly) linked list to make as part of my homework. Of-course I also have a lot to do besides that, but after I get the list out of the way everything should be strait forward, but while I have been using C++ for a while (it was borland C++) a lot of what I knew is either half-forgotten or outdated. I have programmed in python for a while but all that means is that I keep getting frustrated with how pointers work in C++.</p> <p>My problem is when I try to add a new Node to the list, my cursor behaves in an unusual manner, I will explain below:</p> <p><em><strong>EDIT:</em></strong> Ok, I changed the:</p> <pre><code>Node *cursor; cursor = new Node cursor = begin; </code></pre> <p>fiasco, but the result is the same, after the declaration cursor and begin both point at the same memory location (something like: 0x32ce8).</p> <p><em><strong>/EDIT</em></strong></p> <pre><code>Node *add_node (Node *begin,string type, int sum, int ap_nr) // begin is the first node in the list { // if first node is dummy node if (begin->ap_nr == -1) { begin->type = type; begin->ap_nr = ap_nr; begin->sum = sum; begin->next = 0; return begin; } // else create new node and insert it in sorted position else { // EDIT: Node *cursor = begin; // Same problem //if node should be inserted before first node (begin) if (ap_nr <begin->ap_nr) { cursor->ap_nr = ap_nr; cursor->type = type; cursor->sum = sum; cursor->next = begin; return cursor; } </code></pre> <p>Always when I debug, begin has a similar form: 0x32ce02, when I create my "cursor" it has a vastly different form (longer also), but when I do this : cursor = begin, then cursor becomes something like this 0x32df02.</p> <p>However the problem is when I get to "if (ap_nr ap_nr)" then for absolutely no feasible reason cursor becomes: 0x32ce02 and "cursor -> next = begin" ensures an infinite loop. And no matter how many nodes I add this always happens so whenever I print the list it's an infinite stream of the last added Node.</p> <p>Am I doing something wrong ? is it the declaration or the alocation, creation ? something ?</p> <p>Also if I have a pointer *begin somewhere in another module, and with this function I return a new begin ... that should work, right ?</p> <p>P.S. I would also appreciate a simple counter solution (another way to do this if mine is just not good)</p> <p>Also I should point out how I made my list. It is just a simple linking of nodes:</p> <pre><code>struct Node { string type; int ap_nr; int sum; Node *next; }; </code></pre>

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